The IEEE (Institute of Electrical and Electronics Engineers) 802.16 standards propose using an Orthogonal Frequency Division Multiple Access (OFDMA) for transmission of data over an air interface. OFDMA also has been proposed for use in 3GPP (Third Generation Partnership Project) Evolution communication systems. In an OFDMA communication system, a frequency bandwidth is split into multiple contiguous frequency sub-carriers that are transmitted simultaneously. A user may then be assigned one or more of the frequency sub-carriers for an exchange of user information, thereby permitting multiple users to transmit simultaneously on the different sub-carriers. These sub-carriers are orthogonal to each other, and thus intra-cell interference is minimized.
In such systems, voice data is exchanged via Voice over Internet Protocol (VoIP). It is known to improve such systems for VoIP traffic using hybrid automatic repeat request (HARQ) error correction schemes and smaller packet sizes. While VoIP users have the same benefits of advanced link adaptation and statistical multiplexing as data users, the greatly increased number of users that may be served because of the smaller voice packet sizes places a burden on control and feedback mechanisms of the system. For example, it can be easily envisioned that 30 times as many voice packets, and corresponding users, could be served in a given frame than data packets. There are typically about 1600 bytes for data and about 40-50 bytes for voice. However, present downlink resource allocation and acknowledgment mechanisms typically allocate a resource block per user for conveyance of acknowledgments and therefore are not designed to handle such a large number of allocations and consume an inordinate amount of power and bandwidth in order to guarantee accurate detection and decoding at an edge of a cell.
Therefore, a need exists for a method and apparatus that provide for downlink resource allocation and acknowledgments to multiple users and further guarantee accurate detection and decoding at an edge of a cell without consuming an inordinate amount of system power and bandwidth.